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High pass filter

My goal is reduce a vertical axial mode at 60Hz produced from my main speakers.  A JL CR1 did the job but produced too much distortion. I have looked at passive and active line-level crossover and filter options, including DEQX. I am interested in an do-it-myself capacitor option like the one on GR Research website but 6db/octave is too shallow. I need a second order at least. Has anyone made a passive high pass filter second order or higher? I believe it is two capacitors in series with the first one ten times the value as the second. My amp is 30Kohm input impedance. I do not if a resistor is necessary. As I type this I have a sense I am going down the wrong rabbit hole. The relatively low cost and ability to alter it is compelling, though. Thanks for any help. 

ohlala
ohlala OP
1,273 posts
 

Thank  you all for the thoughtful responses. I very well may try a first order filter and will looking to an LC circuit like Erik suggested. Those inexpensive RCA filter plugs would be a simple experiment. The Hsu could also be worth trying, also inexpensive. 

I have a pair of JL fathoms which do not excite that mode. The issue the main speakers. I have done hundreds of measurements and changes over the course of three different speaker pairs. The CR1 fixes the 60Hz anti-node issue. I sold it due to the distortion. A crossover will do the job, but I am trying to not pay the penalty for using one. 

In the past I raised a pair of much lighter REL subs halfway up the wall. It did help. It is a good idea, but I do not want to do raise a 130lb sub off the floor in my living room. I have acoustic treatment including multiple bass traps. For my own sanity I am not going reinvent that wheel ;). That was a long road. Thanks again

mashif
470 posts
 

My room has the same issue. I solved it by using a Marchand 24db HPF at 80hz on the mains. My sub, sitting on the floor, takes over from there. I use an SVS 2000 PRO which has excellent DSP built in to tweak the low end as needed. If your room is large enough, 2 subs are needed. 

pinwa
340 posts
 

You should really just build the GR Research High Pass filters that go between your preamp and amp first before you start mucking around with more expensive/complicated solutions.  You might find that they actually provide exactly what you are looking for. I borrowed a JL CR1 and bought a Marchand and Sublime K235 and ended up using the GR Research filter combined with two SVS SB17 subs.  By rolling off the lows for the main speakers and then tweaking the subs with XO point, phase and PEQ I achieved what I think is exceptional sound.

https://gr-research.com/hi-pass-filters/

The GR Research filters are very easy to build, especially if you are using RCA connections.  I used XLR and that is more time consuming and you need to make sure the caps are closely matched.  Russian Paper in Oil capacitors are cheap and sound good.  Russian teflon are more expensive and sound better.  Auricaps do not sound that good.  I have some expensive teflon caps coming that I am looking forward to trying.

Also, that 60 Hz peak is likely a room mode so playing around with position and bass traps might help.

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